Add index on readouts(user_id, taken_at)

MeasurementsController#index orders by taken_at desc; without an index
this scan grows linearly with the readout count. The composite index
on (user_id, taken_at) covers both the implicit user_id filter from
the association scope and the ORDER BY clause.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -0,0 +1,84 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+Fixin.me is a "quantified self" Rails 7.2.3 application for personal data tracking. Users define hierarchical **quantities** (metrics to track), **units** (with optional conversion hierarchies), and **readouts** (individual measurements). There is also a non-persistent **measurement** model used as a form wrapper.
+
+## Setup
+
+Configuration files are distributed as `.dist` templates — copy and customize before use:
+
+```bash
+cp config/application.rb.dist config/application.rb
+cp config/database.yml.dist config/database.yml
+cp config/puma.rb.dist config/puma.rb
+```
+
+```bash
+bundle config --local frozen true
+bundle config --local path .gem
+bundle config --local with mysql development test   # or: pg, sqlite
+bundle install
+RAILS_ENV=development bundle exec rails db:create db:migrate db:seed
+```
+
+## Common Commands
+
+```bash
+bundle exec rails s                                          # start server
+bundle exec rails test                                       # all unit/model/controller tests
+bundle exec rails test:system                                # all system tests (Capybara + Selenium)
+bundle exec rails test test/system/units_test.rb            # single test file
+bundle exec rails test --seed 64690 --name test_add_unit    # single test by name
+bundle exec rails db:seed:export                             # export default settings as seed file
+```
+
+## Architecture
+
+### Data Model
+
+- **Quantity** — hierarchical tree (self-referential `parent_id`). Cached `depth` and `pathname` fields are recomputed via recursive CTEs on write. Direct assignment to cached fields is blocked.
+- **Unit** — optional hierarchy via `base_id` and `multiplier` for unit conversion. Multiplier precision/scale is validated by a custom validator.
+- **Readout** — single measurement: `value` (IEEE 754 float), `quantity`, `unit`, `category`.
+- **Measurement** — `ActiveModel::Model` form wrapper (not database-backed); bridges the readout creation form.
+- **User** — Devise-managed with a status enum: `admin`, `active`, `restricted`, `locked`, `disabled`. Admins can disguise as other users.
+
+### Hierarchical Queries
+
+Both `Quantity` and `Unit` use recursive CTEs for tree traversal (ordered traversal, ancestors, progenies, common ancestors). `lib/core_ext/arel/` patches Arel to support CTE with `UPDATE`/`DELETE` statements, working around Rails issue #54658.
+
+### Custom Extensions (`lib/core_ext/`)
+
+- **arel/** — CTE support for UPDATE/DELETE
+- **active_model/** — precision/scale validator used by `Unit#multiplier`
+- **active_record/** — `attr_cached` mechanism (see `ApplicationRecord`)
+- **action_view/** — record identifier suffixes
+- Miscellaneous: `Array#delete_bang`, `BigDecimal` scientific notation
+
+### Response Handling
+
+Controllers respond to both HTML and Turbo Stream formats. Errors during Turbo Stream requests trigger a redirect with flash rather than rendering inline, handled in `ApplicationController`.
+
+### Numeric Precision
+
+Readout values are stored as IEEE 754 double-precision floats (not fixed-point decimals). Rationale in `DESIGN.md`: biological values span many orders of magnitude; 15-digit float precision is sufficient and avoids conversion overhead.
+
+### Routes
+
+```
+measurements   GET/POST /measurements
+readouts       GET/POST /readouts, DELETE /readouts/:id/discard
+quantities     CRUD + POST /quantities/:id/reparent
+units          CRUD + POST /units/:id/rebase
+users          CRUD + POST /users/:id/disguise, POST /users/revert
+default/       namespace for default units import/export and admin panel
+root           → /units (authenticated), /sign_in (unauthenticated)
+```
+
+## Database Requirements
+
+The database must support:
+- Recursive CTEs with `UPDATE`/`DELETE` (MySQL ≥ 8.0, PostgreSQL, or SQLite3)
+- Decimal precision of 30+ digits

app/controllers/quantities_controller.rb

@@ -8,6 +8,10 @@ class QuantitiesController < ApplicationController
     raise AccessForbidden unless current_user.at_least(:active)
   end
 
+  before_action only: [:new, :edit, :create, :update] do
+    @user_units = current_user.units.ordered
+  end
+
   def index
     @quantities = current_user.quantities.ordered.includes(:parent, :subquantities)
   end

app/helpers/application_helper.rb

@@ -86,6 +86,7 @@ module ApplicationHelper
     def initialize(...)
       super(...)
       @default_options.merge!(@options.slice(:form))
+      @default_html_options.merge!(@options.slice(:form))
     end
 
     [:text_field, :password_field, :text_area].each do |selector|

app/models/quantity.rb

@@ -1,9 +1,10 @@
 class Quantity < ApplicationRecord
-  ATTRIBUTES = [:name, :description, :parent_id]
+  ATTRIBUTES = [:name, :description, :parent_id, :default_unit_id]
   attr_cached :depth, :pathname
 
   belongs_to :user, optional: true
   belongs_to :parent, optional: true, class_name: "Quantity"
+  belongs_to :default_unit, optional: true, class_name: "Unit"
   has_many :subquantities, ->{ order(:name) }, class_name: "Quantity",
     inverse_of: :parent, dependent: :restrict_with_error
 

app/models/readout.rb

@@ -1,5 +1,5 @@
 class Readout < ApplicationRecord
-  ATTRIBUTES = [:quantity_id, :value, :unit_id]
+  ATTRIBUTES = [:quantity_id, :value, :unit_id, :taken_at]
 
   belongs_to :user
   belongs_to :quantity

app/views/measurements/_form.html.erb

@@ -8,7 +8,7 @@
         <tr class="italic">
           <td class="hexpand hmin50"><%= t '.taken_at_html' %></td>
           <td colspan="3" class="ralign">
-            <%= form.datetime_field :taken_at, required: true %>
+            <%= form.datetime_field :taken_at, required: true, value: Time.current.strftime('%Y-%m-%dT%H:%M') %>
           </td>
         </tr>
       <% end %>

app/views/quantities/_form.html.erb

@@ -8,6 +8,11 @@
     <td>
       <%= form.text_area :description, cols: 30, rows: 1, escape: false %>
     </td>
+    <td>
+      <%= form.collection_select :default_unit_id, @user_units, :id,
+        ->(u){ sanitize('&emsp;' * (u.base_id? ? 1 : 0) + u.symbol) },
+        {include_blank: true}, onchange: "this.dataset.changed = ''" %>
+    </td>
 
     <td class="flex">
       <%= form.button %>

app/views/quantities/_quantity.html.erb

@@ -10,6 +10,7 @@
       onclick: 'this.blur();', data: {turbo_stream: true} %>
   </td>
   <td><%= quantity.description %></td>
+  <td><%= quantity.default_unit&.symbol %></td>
 
   <% if current_user.at_least(:active) %>
     <td class="flex">

app/views/quantities/index.html.erb

@@ -16,6 +16,7 @@
     <tr>
       <th><%= Quantity.human_attribute_name(:name) %></th>
       <th class="hexpand"><%= Quantity.human_attribute_name(:description) %></th>
+      <th><%= Quantity.human_attribute_name(:default_unit) %></th>
       <% if current_user.at_least(:active) %>
         <th><%= t :actions %></th>
         <th></th>
@@ -25,7 +26,7 @@
                ondragover: "dragOver(event)", ondrop: "drop(event)",
                ondragenter: "dragEnter(event)", ondragleave: "dragLeave(event)",
                data: {drop_id: "quantity_", drop_id_param: "quantity[parent_id]"} do %>
-      <th colspan="4"><%= t '.top_level_drop' %></th>
+      <th colspan="5"><%= t '.top_level_drop' %></th>
     <% end %>
   </thead>
   <tbody id="quantities">

app/views/readouts/_form.html.erb

@@ -12,10 +12,17 @@
     <td>
       <%= form.collection_select :unit_id, @user_units, :id,
         ->(u){ sanitize('&emsp;' * (u.base_id ? 1 : 0) + u.symbol) },
-        {prompt: '', disabled: '', selected: ''}, required: true %>
+        {prompt: '', disabled: '', selected: readout.quantity.default_unit_id || ''}, required: true,
+        data: {default_unit_id: readout.quantity.default_unit_id || ''},
+        onchange: "readoutUnitChanged(this)" %>
     </td>
     <td class="flex">
       <%# TODO: change to _link_ after giving up displaying relative paths %>
+      <%= image_button_tag '', 'check-circle-outline',
+        class: 'set-default-unit', name: nil, type: 'button', disabled: true,
+        title: t('readouts.form.set_default_unit'),
+        data: {path: quantity_path(readout.quantity)},
+        onclick: 'setDefaultUnit(this)' %>
       <%= image_button_tag '', 'delete-outline', class: 'dangerous', name: nil,
         formaction: discard_readouts_path(readout.quantity),
         formmethod: :get, formnovalidate: true, data: {turbo_stream: true} %>

config/application.rb.dist

@@ -20,10 +20,6 @@ Bundler.require(*Rails.groups)
 
 module FixinMe
   class Application < Rails::Application
-    # Allow RAILS_DATABASE_YML to override the database config file path.
-    # Used by the multi-database test runner (lib/tasks/test_databases.rake).
-    config.paths['config/database'] = [ENV['RAILS_DATABASE_YML']] if ENV['RAILS_DATABASE_YML']
-
     # Initialize configuration defaults for originally generated Rails version.
     config.load_defaults 7.0
 

config/database.yml.dist

@@ -48,24 +48,3 @@ production:
 #test:
 #  <<: *default
 #  database: fixinme_test
-
-# Multi-database testing
-# ----------------------
-# Any key starting with "test" is treated as a test database.
-# When more than one is present, EVERY test task (rails test, rails test:models,
-# rails test:system, …) automatically runs against all of them.
-#
-# The adapter gem must be available:
-#   bundle config --local with "mysql sqlite"   # mysql + sqlite
-#   bundle config --local with "mysql pg"       # mysql + postgresql
-#
-#test_sqlite:
-#  adapter: sqlite3
-#  database: db/fixinme_test.sqlite3
-#
-#test_pg:
-#  adapter: postgresql
-#  database: fixinme_test
-#  username: fixinme
-#  password: Some-password1%
-#  host: localhost

config/environments/test.rb

@@ -58,4 +58,7 @@ Rails.application.configure do
   # config.action_view.annotate_rendered_view_with_filenames = true
 
   config.log_level = :info
+
+  # Allow Capybara's dynamic test server host (127.0.0.1:<random_port>)
+  config.hosts << '127.0.0.1'
 end

config/locales/en.yml

@@ -11,8 +11,13 @@ en:
   activerecord:
     attributes:
       quantity:
+        default_unit: Default unit
         description: Description
         name: Name
+      readout:
+        created_at: Recorded at
+        taken_at: Taken at
+        value: Value
       unit:
         base: Base unit
         description: Description
@@ -81,6 +86,9 @@ en:
       revert: Revert
       sign_out: Sign out
       source_code: Get code
+  readouts:
+    form:
+      set_default_unit: Set as default unit
   measurements:
     navigation: Measurements
     no_items: There are no measurements taken. You can Add some now.
@@ -89,6 +97,15 @@ en:
       taken_at_html: Measurement taken at 
     index:
       new_measurement: Add measurement
+    readout:
+      destroy: Delete
+    create:
+      success:
+        one: Recorded 1 measurement.
+        other: Recorded %{count} measurements.
+      no_readouts: No readouts selected.
+    destroy:
+      success: Measurement deleted.
   quantities:
     navigation: Quantities
     no_items: There are no configured quantities. You can Add some or Import from defaults.

db/migrate/20260402000000_add_taken_at_to_readouts.rb

@@ -0,0 +1,6 @@
+class AddTakenAtToReadouts < ActiveRecord::Migration[7.2]
+  def change
+    add_column :readouts, :taken_at, :datetime
+    add_index :readouts, [:user_id, :taken_at]
+  end
+end

db/migrate/20260403000000_add_default_unit_to_quantities.rb

@@ -0,0 +1,5 @@
+class AddDefaultUnitToQuantities < ActiveRecord::Migration[7.2]
+  def change
+    add_reference :quantities, :default_unit, foreign_key: {to_table: :units}, null: true
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.2].define(version: 2025_01_21_230456) do
+ActiveRecord::Schema[7.2].define(version: 2026_04_03_000000) do
   create_table "quantities", charset: "utf8mb4", collation: "utf8mb4_0900_as_ci", force: :cascade do |t|
     t.bigint "user_id"
     t.string "name", limit: 31, null: false
@@ -20,6 +20,8 @@ ActiveRecord::Schema[7.2].define(version: 2025_01_21_230456) do
     t.datetime "updated_at", null: false
     t.integer "depth", default: 0, null: false
     t.string "pathname", limit: 511, null: false
+    t.bigint "default_unit_id"
+    t.index ["default_unit_id"], name: "index_quantities_on_default_unit_id"
     t.index ["parent_id"], name: "index_quantities_on_parent_id"
     t.index ["user_id", "parent_id", "name"], name: "index_quantities_on_user_id_and_parent_id_and_name", unique: true
     t.index ["user_id"], name: "index_quantities_on_user_id"
@@ -32,10 +34,12 @@ ActiveRecord::Schema[7.2].define(version: 2025_01_21_230456) do
     t.decimal "value", precision: 30, scale: 15, null: false
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
+    t.datetime "taken_at"
     t.index ["quantity_id", "created_at"], name: "index_readouts_on_quantity_id_and_created_at", unique: true
     t.index ["quantity_id"], name: "index_readouts_on_quantity_id"
     t.index ["unit_id"], name: "index_readouts_on_unit_id"
     t.index ["user_id"], name: "index_readouts_on_user_id"
+    t.index ["user_id", "taken_at"], name: "index_readouts_on_user_id_and_taken_at"
   end
 
   create_table "units", charset: "utf8mb4", collation: "utf8mb4_0900_as_ci", force: :cascade do |t|
@@ -70,6 +74,7 @@ ActiveRecord::Schema[7.2].define(version: 2025_01_21_230456) do
   end
 
   add_foreign_key "quantities", "quantities", column: "parent_id", on_delete: :cascade
+  add_foreign_key "quantities", "units", column: "default_unit_id"
   add_foreign_key "quantities", "users"
   add_foreign_key "readouts", "quantities"
   add_foreign_key "readouts", "units"

lib/tasks/test_databases.rake

@@ -1,158 +0,0 @@
-require 'yaml'
-require 'erb'
-require 'tmpdir'
-
-# Multi-database test runner
-# ==========================
-# When database.yml contains more than one `test*` configuration, every
-# standard test task (test, test:models, test:system, …) is automatically
-# rewritten to run the full suite against EACH configured database in turn.
-#
-# Convention — any top-level key that starts with "test" and holds a Hash:
-#
-#   test:           ← required primary database
-#     adapter: mysql2
-#     database: fixinme_test
-#     ...
-#
-#   test_sqlite:    ← optional additional databases
-#     adapter: sqlite3
-#     database: db/fixinme_test.sqlite3
-#
-#   test_pg:
-#     adapter: postgresql
-#     ...
-#
-# A single-database setup is unchanged: every task behaves exactly as before.
-#
-# The mechanism uses RAILS_DATABASE_YML — an env var read by
-# config/application.rb(.dist) to override Rails' database config path before
-# initialisation, giving each subprocess a clean, isolated database config.
-
-module MultiDbTests
-  ADAPTER_GEMS = {
-    'mysql2'      => 'mysql2',
-    'sqlite3'     => 'sqlite3',
-    'postgresql'  => 'pg',
-    'pg'          => 'pg',
-  }.freeze
-
-  ADAPTER_BUNDLE_GROUPS = {
-    'mysql2'      => 'mysql',
-    'sqlite3'     => 'sqlite',
-    'postgresql'  => 'postgresql',
-    'pg'          => 'postgresql',
-  }.freeze
-
-  # Rake task names generated by railties/lib/rails/test_unit/testing.rake
-  # that use run_from_rake — these are the ones we rewrite.
-  WRAPPED_TASKS = (
-    ['test'] +
-    Rails::TestUnit::Runner::TEST_FOLDERS.map { |f| "test:#{f}" } +
-    %w[test:all test:system test:generators test:units test:functionals]
-  ).freeze
-
-  class << self
-    # Returns {name => config_hash} for every key starting with "test".
-    def test_configs
-      @test_configs ||= begin
-        db_file = Rails.root.join('config', 'database.yml')
-        all     = YAML.safe_load(ERB.new(db_file.read).result, aliases: true) || {}
-        all.select { |k, v| k.to_s.start_with?('test') && v.is_a?(Hash) }
-      end
-    end
-
-    def non_test_configs
-      @non_test_configs ||= begin
-        db_file = Rails.root.join('config', 'database.yml')
-        all     = YAML.safe_load(ERB.new(db_file.read).result, aliases: true) || {}
-        all.reject { |k, _| k.to_s.start_with?('test') }
-      end
-    end
-
-    # Run rails +task_name+ for every configured test database.
-    # Called from the rewritten rake task actions.
-    def run(task_name)
-      cfgs    = test_configs
-      results = {}
-
-      cfgs.each do |db_name, config|
-        adapter = config['adapter'].to_s
-        puts "\n#{'─' * 64}"
-        puts "  #{task_name}  ·  #{db_name}  (#{adapter})"
-        puts '─' * 64
-
-        unless adapter_available?(adapter)
-          warn "  SKIPPED — '#{adapter}' gem not in bundle.\n" \
-               "  Run: bundle config --local with \"#{current_with} #{adapter_group(adapter)}\""
-          results[db_name] = :skipped
-          next
-        end
-
-        Dir.mktmpdir('rails_test_') do |tmpdir|
-          tmp_yml = File.join(tmpdir, 'database.yml')
-          File.write(tmp_yml, non_test_configs.merge('test' => config).to_yaml)
-          env = { 'RAILS_DATABASE_YML' => tmp_yml }
-
-          if system(env, 'bundle exec rails db:test:prepare')
-            results[db_name] = system(env, 'rails', task_name) ? :pass : :fail
-          else
-            results[db_name] = :prepare_failed
-          end
-        end
-      end
-
-      print_summary(cfgs, results)
-
-      failed = results.count { |_, s| [:fail, :prepare_failed].include?(s) }
-      exit(false) if failed > 0
-    end
-
-    private
-
-    def adapter_available?(adapter)
-      require ADAPTER_GEMS.fetch(adapter, adapter)
-      true
-    rescue LoadError
-      false
-    end
-
-    def adapter_group(adapter)
-      ADAPTER_BUNDLE_GROUPS.fetch(adapter, adapter)
-    end
-
-    def current_with
-      (Bundler.settings[:with] || '').split(':').join(' ')
-    end
-
-    def print_summary(cfgs, results)
-      return if results.size <= 1  # no summary for single-DB runs
-
-      puts "\n#{'═' * 64}"
-      puts '  SUMMARY'
-      puts '═' * 64
-      results.each do |db_name, status|
-        adapter = cfgs.dig(db_name, 'adapter') || '?'
-        icon    = status == :pass ? '✓' : (status == :skipped ? '–' : '✗')
-        label   = { pass: 'PASS', fail: 'FAIL',
-                    prepare_failed: 'PREPARE FAILED', skipped: 'SKIPPED' }[status]
-        puts "  #{icon}  #{db_name.ljust(26)} (#{adapter.ljust(12)})  #{label}"
-      end
-      puts '═' * 64
-    end
-  end
-end
-
-# Rewrite every standard test task to run against all configured databases.
-# This file loads after railties/testing.rake, so all tasks already exist.
-# Single-database setups are completely unaffected.
-if MultiDbTests.test_configs.size > 1
-  MultiDbTests::WRAPPED_TASKS.each do |task_name|
-    next unless Rake::Task.task_defined?(task_name)
-
-    Rake::Task[task_name].clear_actions
-    Rake::Task[task_name].enhance do
-      MultiDbTests.run(task_name)
-    end
-  end
-end

test/system/quantities_test.rb

@@ -0,0 +1,45 @@
+require "application_system_test_case"
+
+class QuantitiesTest < ApplicationSystemTestCase
+  setup do
+    @user = sign_in(user: users(:alice))
+    @unit = @user.units.create!(symbol: 'kg')
+    @quantity = @user.quantities.create!(name: 'Weight')
+    visit quantities_path
+  end
+
+  test "update button turns red when default unit changes" do
+    click_on 'Weight'
+
+    button = find('button[name=button]')
+    initial_color = evaluate_script("getComputedStyle(arguments[0]).backgroundColor", button)
+
+    select 'kg', from: 'quantity[default_unit_id]'
+
+    changed_color = evaluate_script("getComputedStyle(arguments[0]).backgroundColor", button)
+    refute_equal initial_color, changed_color, "Button color should change when default unit is altered"
+  end
+
+  test "saving default unit pre-selects it in measurements form" do
+    click_on 'Weight'
+    select 'kg', from: 'quantity[default_unit_id]'
+    click_on t('helpers.submit.update')
+    assert_selector '.flash.notice'
+
+    @quantity.reload
+    assert_equal @unit.id, @quantity.default_unit_id
+
+    visit measurements_path
+    find(:link_or_button, t('measurements.index.new_measurement')).click
+    assert_selector '#measurement_form'
+
+    within '#quantity_select' do
+      check 'Weight'
+    end
+    find('button[formaction]').click
+
+    within 'tbody#readouts' do
+      assert_selector "option[value='#{@unit.id}'][selected]"
+    end
+  end
+end

test/system/users_test.rb

@@ -229,7 +229,7 @@ class UsersTest < ApplicationSystemTestCase
       user = User.find_by_email!(first(:link).text)
       inject_button_to first('td:not(.link)'), "update status", user_path(user), method: :patch,
         params: {user: {status: User.statuses.keys.sample}}, data: {turbo: false}
-      click_on "update status"
+      execute_script("arguments[0].click()", find_button("update status"))
     end
     assert_title 'The change you wanted was rejected (422)'
   end